1. Field of Invention
This invention is directed to cartridges for inkjet printing. In particular, this invention is directed to gasket seals for sealing a cover of a cartridge for inkjet printing to the cartridge body.
2. Description of Related Art
Numerous printing apparatuses employ inkjet cartridges to perform their printing functions. Inkjet cartridges generally include containers for storing ink and for delivering that ink to a printhead. It is often necessary to store the ink in a partial vacuum environment. In operation, it is preferable that ink does not escape from the container for storing ink. Similarly, it is preferable that various elements in the environment of the ink cartridge not enter into the container for storing ink. These preferable conditions are often maintained by forming a seal between a cover and the container for storing ink to isolate the container from its environment. Ideally, such seals will not adversely affect the ink stored in the container. To manufacture inkjet cartridges simply and economically, it also preferable that the seal be applied in a consistent and reliable manner. Also, it is desirable that the seal be such that it is possible to unseal and reseal the inkjet cartridge.
One known approach for sealing a cover to a container for storing ink in an inkjet cartridge is to employ an adhesive. A shortcoming of such an approach is that seals formed using adhesives can degrade upon contact with the ink stored in the container. Alternatively, some adhesives employed in such an application will adversely affect the ink. Use of adhesives to seal containers for storing inks in inkjet cartridges can also complicate manufacture. Manufacture can be complicated by the length of time necessary to cure adhesives. Also, inconsistencies in adhesive compositions can result in inconsistencies in the seals from inkjet cartridge to inkjet cartridge. Further, when heat is used to cure adhesives, such heat can damage portions of the inkjet cartridge unrelated to the seal.
Another known approach for sealing a cover to a container for storing ink in an inkjet cartridge is to employ welding techniques, such as ultrasonic welding. In order to employ an approach such as ultrasonic welding, the parts to be sealed (i.e., the cover and the container for storing ink) must be parts compatible with welding processes. Often such is not the case in inkjet cartridge manufacture. Further, the welding energy can heat, melt and/or crack unrelated parts of the inkjet cartridge, which can damage those unrelated portions. Ultrasonic welding also necessitates exacting manufacturing conditions. For example, the parts to be welded must be generally planar at the surfaces to be welded and the pieces to be welded must be supported in precise positions. Such requirements can enhance the complexity, and thus cost, of manufacture. Further, damage to an ultrasonic seal is extremely difficult to repair.
Employing welding techniques to seal a cover to a container for storing ink also creates difficulties relating to the types of materials that can be used to form the ink container and the cover. For example, some materials, such as liquid crystal polymer (LCP) and DELRIN, simply are not suitable for welding. Problems are also presented when different materials are used to form the ink container and the cover. For example, one or both of the materials may be unsuitable for welding. Alternatively, the conditions under which welding must be conducted may differ between the material used to form the ink container and the material used to form the cover.
A further approach for sealing a cover to a container for storing ink in an inkjet cartridge is to employ a gasket between the cover and the container. The gasket is generally “sandwiched” between the cover and container, and requires that pressure be applied mechanically to hold the cover and container together. The gasket in such an arrangement exerts a force that acts to separate the cover from the container. The mechanical means used to hold cover, gasket and container together can degrade and/or adversely affect the ink stored in the cartridge.
A still further approach for sealing a cover to a container for storing ink in an inkjet cartridge is described in U.S. Pat. No. 6,286,950, which is incorporated herein by reference in its entirety. This approach involves inserting the cover into the container, and situating a gasket between the portion of the cover that is inserted into the container and an inner wall of the container. The gasket forms a seal between the cover and the receptacle, and the force exerted by the gasket as to the parts with which it is in contact is normal, rather than parallel, to the direction in which those parts are connected.